XML (Extensible Mark-up Language) is designed to represent hierarchical structures; in this case, it shows the structure of the prosodic components of spoken language. The XML-based transcription system proposed here allows the input of 1) the phonetic parameters of F0, intensity and duration of each syllable, their relative variation and standard values to facilitate discrimination and comparison; 2) the distribution of feet; 3) the boundaries and characterization of intonation units and utterances, and 4) other conversational phenomena such as pauses, overlaps, interruptions, etc. This mark-up language is currently being used as an analysis tool for a corpus of digitally-recorded conversations in the Mexican and Iberian vernaculars of spoken Spanish.